1. Technical Field
The present invention relates to a wireless charging system and, more particularly, to a wireless charging system capable of reducing waste of power.
2. Description of the Related Art
Recently, research on a wireless power transfer technique that allows convenient supplying or charging power without having connection of an electric wire to various electronic devices has been actively ongoing, such that the field for the wireless power transfer technology is rapidly growing.
The wireless power transfer technique has expended from a scheme of wirelessly charging personal terminals to a technique of wirelessly charging vehicle batteries.
The wireless power transfer technique field is classified into three schemes, i.e., an inductive coupling scheme, an evanescent wave resonance scheme, and a radio frequency (RF) scheme, and currently, the inductive coupling scheme is commonly used because it is very effective.
The inductive coupling scheme has the same basic principle as that of a transformer, and, in a wireless charging system, primary and secondary coils of a transformer are separately used. Namely, the primary coil is used in a charging device (referred to as a ‘transmission device’, hereinafter) and the secondary coil is mounted in a terminal (referred to as a ‘reception device’, hereinafter) so as to be used.
In designing a wireless charging system using the inductive coupling scheme, an induction of current between coils is closely related to the efficiency of the overall system, so the wireless charging system should be designed in consideration of the coil characteristics and matching of the transmitter and the receiver.
In addition, an unnecessary waste of power at the transmission device's side should be necessarily reduced by determining the presence or absence of the reception device on a transmission device pad; namely, transmitting power when the reception device is present thereon and preventing power supply in the absence of the reception device.